I thought I was being informative. I can't give hard&fast rules because (drumroll)... it depends. So I have tradeoffs to consider, and indexes got mentioned.

How else could I have posted better? Honest question.

Because you didn’t actually refute anything the GP said, and gave bad advice, all while being incredibly negative and arrogant.

> this mostly clueless advice

> strong opinions put forth by someone who doesn't have the necessary experience, or understanding of what's going on under the hood

> I'm tired of suchlike n00b advice strongly (and incorrectly and arrogantly) expressed on HN

You continue to just say it depends without giving any actual scenarios. You make it sound like magic, but it’s not: “under x and y, do z except when u” is better than “it depends, I’m sick of all these noobs”.

Also, your main points are against denormalization and avoiding large table joins which are 100% rational arguments under certain workloads.

I refuted what he said by pointing out that 1E9 x 1E6 = 1E15. A billion row table denormalised with a million row table = 1000 trillion row table. How big's your disk array? How are you going to ensure correctness on update?

His was stupid advice and had it should not have been given.

> You continue to just say it depends without giving any actual scenarios

it depends. Use your common sense and then use a stopwatch, is a good start. There are entire shelves of books on this, I won't repeat them.

> You make it sound like magic, but it’s not:

absolutely true!

> “under x and y, do z except when u” is better than

it's a multidimensional problems inc. memory size, disk size, the optimiser, sizes of particular tables joined, where the hotspot is, cost of updates of non-normalised tables, etc. I can't give general advice from here.

> Also, your main points are against denormalization and avoiding large table joins which are 100% rational arguments under certain workloads.

I said "Denormalising is a useful tool that IME rarely gains you more than it loses you,"

I don't accept your criticism.

That’s not what denormalize means, how long have you been doing this again?

True, you normalise/denormalise data not tables as such; tables pop out of a normalisation process and denormalisation collapses them together. Perhaps if I'm still wrong you could put me right. And don't just point at the wiki article on it, please be specific.

To your question, probably longer than you but I've always more to learn.